26,830 research outputs found
Proposal for a High Energy Nuclear Database
We propose to develop a high-energy heavy-ion experimental database and make
it accessible to the scientific community through an on-line interface. This
database will be searchable and cross-indexed with relevant publications,
including published detector descriptions. Since this database will be a
community resource, it requires the high-energy nuclear physics community's
financial and manpower support. This database should eventually contain all
published data from Bevalac, AGS and SPS to RHIC and LHC energies,
proton-proton to nucleus-nucleus collisions as well as other relevant systems,
and all measured observables. Such a database would have tremendous scientific
payoff as it makes systematic studies easier and allows simpler benchmarking of
theoretical models to a broad range of old and new experiments. Furthermore,
there is a growing need for compilations of high-energy nuclear data for
applications including stockpile stewardship, technology development for
inertial confinement fusion and target and source development for upcoming
facilities such as the Next Linear Collider. To enhance the utility of this
database, we propose periodically performing evaluations of the data and
summarizing the results in topical reviews.Comment: 8 pages, 3 figures. Proceedings of the 21st Winter Workshop on
Nuclear Dynamics, Breckenridge, Colorado, February 5--12, 200
Parton densities and structure functions at next-to-next-to-leading order and beyond
We summarize recent results on the evolution of unpolarized parton densities
and deep-inelastic structure functions in massless perturbative QCD. Due to
last year's extension of the integer-moment calculations of the three-loop
splitting functions, the NNLO evolution of the parton distributions can now be
performed reliably at momentum fractions x >= 10^-4, facilitating a
considerably improved theoretical accuracy of their extraction from data on
deep-inelastic scattering. The NNLO corrections are not dominated, at relevant
values of x, by their leading small-x terms. At large x the splitting-function
series converges very rapidly, hence, employing results on the three-loop
coefficient functions, the structure functions can be analysed at N^3LO for x >
10^-2. The resulting values for alpha_s do not significantly change beyond
NNLO, their renormalization scale dependence reaches about +-1% at N^3LO.Comment: 10 pages, LaTeX, 6 figures. Talk presented at the workshops `New
Trends in HERA Physics 2001', Ringberg Castle (Germany), June 2001 and `DIS
2001', Bologna (Italy), April 2001. To appear, slightly shortened in the
latter case, in the proceeding
Suited for spacewalking: A teacher's guide with activities
This publication is an activity guide for teachers on spacesuits and spacewalking. It uses the intensive interest many children have in space exploration as a launching point for hands-on-opportunities. The guide begins with brief discussions of the space environment, the history of space walking, the Space Shuttle spacesuit, and working in space. These are followed by a series of activities that enable children to explore the space environment as well as the science and technology behind the functions of spacesuits. The activities are not rated for specific grade levels because they can be adapted for students of many ages. The guide concludes with a brief glossary as well as references and resources
Labor Rights in the Generalized System of Preferences: A 20-Year Review
[Excerpt]In the fall of 1982, a small group of labor, religious, and human rights activists began charting a new course for human rights and workers\u27 rights in American trade policy. The principles of these labor rights advocates were straightforward:
1. No country should attract investment or gain an edge in international trade by violating workers\u27 rights;
2. No company operating in global trade should gain a competitive edge by violating workers\u27 rights; and,
3. Workers have a right to demand protection for labor rights in the international trade system, and to have laws to accomplish it.
The coalition that took shape 20 years ago made a labor rights amendment to the Generalized System of Preferences (GSP), the chief policy vehicle in U.S. law to promote these principles. This article reviews 20 years\u27 experience with the GSP labor rights clause
The Quark Form Factor at Higher Orders
We study the electromagnetic on-shell form factor of quarks in massless
perturbative QCD. We derive the complete pole part in dimensional
regularization at three loops, and extend the resummation of the form factor to
the next-to-next-to-leading contributions. These results are employed to
evaluate the infrared finite absolute ratio of the time-like and space-like
form factors up to the fourth order in the strong coupling constant. Besides
for the pole structure of higher-loop QCD amplitudes, our new contributions to
the form factor are also relevant for the high-energy limit of massive gauge
theories like QED. The highest-transcendentality component of our results
confirms a result recently obtained in N=4 Super-Yang-Mills theory.Comment: 16 pages, 1 figure, Late
Parton densities and structure functions beyond the next-to-leading order
We briefly discuss recent results on the evolution of unpolarized parton
densities and structure functions in massless perturbative QCD. Present partial
results on the next-to-next-to-leading order (NNLO) evolution kernels prove
sufficient for reliable calculations at not too small values of the Bjorken
variable, x > 10^-3. One order more can be taken into account at x >= 0.2.
Inclusion of these terms considerably reduces the main theoretical
uncertainties of determinations of alpha_s (to about 1% at the Z-mass) and the
parton densities from structure functions.Comment: 6 pages LaTeX including 6 eps-figures. Talk presented at `Loops and
Legs in Quantum Field Theory', Bastei (Germany) April 2000. To appear in the
proceedings [Nucl. Phys. B (Proc. Suppl.)
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